PDA

View Full Version : Securing Rack Storage Legs To Floor



Insurance Engineer
January 14th, 2010, 06:29
Do you review racks and how they are secured to the floor to prevent movement? Do you think these racks were secured?

http://www.youtube.com/watch?v=UAsZ3PQoL5k

Typically how many bolts do you see per leg support? In section 2208, Steel Storage Racks in IBC 2006 it refers you to an ASCE 7. What information do you typically receive to meet this requirement? I typically see 1 bolt per leg of a rack. In active seismic zones what do you typically see?

Thanks

vegas paul
January 14th, 2010, 10:04
We require special inspection (per 1707.6) for anchorage due to our seismic cat. D for any racks above 8 ft. high. Typically, a structural design is required to address lateral and seismic loads.

mtlogcabin
January 14th, 2010, 10:07
Require engineered stamped drawings and special inspection per IBC 1707.6

High Desert
January 14th, 2010, 11:35
Depending upon the height, commodity and seimic category, you could see from one to four anchors per leg. I've never seen a design less than two anchors per leg. We always require a design and structural calculations not only for the anchors, but also the rack components.

D a v e W
January 17th, 2010, 19:09
We see two bolts per leg with corner guards at the isle ends. Of course this would have helped in the case as it was struct in the middle.

If I may expand this thread a little.

What about the weight of an object, 400lbs or heavier. Would engineering be required for achorage for other than tipping over. Or would lateral movement be of concern as well. Lets say zone D2. Thanks!

mtlogcabin
January 17th, 2010, 19:45
What about the weight of an object, 400lbs or heavier. Would engineering be required for achorage for other than tipping over. Or would lateral movement be of concern as well. Lets say zone D2. Thanks!

Yes All tanks, transformers, RTU's. It has been a battlet with the some of the trades, but never lost one

mark handler
January 18th, 2010, 09:19
Bolting the legs to the floor will not prevent this type of collapse

Pcinspector1
January 18th, 2010, 10:02
Insurance Engineer,

Has there been an investigation on this accident released?
If so, what was the outcome?

It appears the plywood on the forklift knocked out the cross member when it hit the post, which pulled the stacked items onto each other causing the domino affect. From the video it appears the pallet racks post stayed in place until an overload happened.

Just wondering

D a v e W
January 18th, 2010, 20:42
MT, just anchorage or full blown engineering? Generally we see 1/2' X 3 1/2" wedge anchors specified or smaller each time. Just wondering how maybe everyone else handles it. :D

jar546
January 19th, 2010, 22:31
Just got a set of prints for a large rack system today. We are seismic category B so the special inspections don't apply.

Other than manufacturer's installation requirements and ensuring sprinklers will not be affected, I don't see much do do with these since people will not be on them.

mtlogcabin
January 19th, 2010, 23:25
Dave
Most of the time the structural engineer will make the call on the attachments usually with a letter or detail. Don't ask for a seal or stamp on it unless it is a life safety piece of equipment. Seeing a lot of "Titen" bolts being used now in lieu of the wedge anchors.

http://www.simpsonanchors.com/catalog/m ... index.html (http://www.simpsonanchors.com/catalog/mechanical/titen-hd/index.html)

D a v e W
January 20th, 2010, 08:52
MT, yes titan bolts, sure make life easy! :D I just wish the MFG would add this to the instruction! :roll:

FyrBldgGuy
January 20th, 2010, 09:40
I am sorry but you all have missed the point of the video. This is a progressive collapse of a rack system. The old UBC had a requirement for protection of racks where impacts were possible. The IBC does not have any required protection from this type of an accident. Bolting the legs to the floor will not prevent, delay or slow down a progressive collapse.

The requirements for safety factors on racks can be found in http://www.mhia.org/learning/resources/freedownloads/7977/specification-for-the-design-testing-and-utilization-of-industrial-steel-storage-racks-ansi-mh16-1-2008 for racks that do not have building structural loads. Where the IBC sends you to ASCE 7, you still won't find a specific requirement to limit impact damage, or measures to prevent a progressive collapse.

When you visit a Big Box Store or a Rack Supported Structure take a look really close. Do you see stiffeners or designed weak members that are specifically designed to prevent a progressive collapse?

If one cell in a rack is designed for 1000 pounds of storage, and the rack uprights carry 6 cells that is 6000 pounds on the uprights. If one set of uprights between two sets of cells has a failure the combined weight of all cells transfers to the adjacent uprights. The weight of the adjoing cells can as much as double within a fraction of a second. If the adjoining uprights fail, now that weight increases again. The problem becomes almost logrithmic.

So how many bolts are required? Not even the jury could tell you. Been there done that. And although information was presented to the ICC, no changes to the code have occured.

So what building official signed off on that rack? Why didn't it have impact protection?
http://www.jsonline.com/business/29466909.html